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Publication Open Access Computational analysis of binding between malarial dihydrofolate reductases and anti-folates(2010-03-02) Kiattawee Choowongkomon; Sasikrit Theppabutr; Napat Songtawee; Day, Nicholas P.J.; White, Nicholas J; Woodrow, Charles J.; Mallika Imwong; มัลลิกา อิ่มวงศ์; Mallika Imwong; Mahidol University. Faculty of Tropical Medicine. Department of Clinical Tropical Medicine.constructed using the solved PfDHFR-TS and PvDHFR structures respectively as templates. The modelled structures were docked with three DHFR inhibitors as ligands and more detailed interactions were explored via simulation of molecular dynamics. ResultsPublication Open Access Microsatellite genotyping of Plasmodium vivax infections and their relapses in pregnant and non-pregnant patients on the Thai-Myanmar border(2013) Supinya Thanapongpichat; McGready, Rose; Luxemburger, Christine; Day, Nicholas PJ.; White, Nicholas J.; Nosten, Francois; Snounou, Georges; Mallika Imwong; Mahidol University. Faculty of Tropical Medicine. Molecular Tropical Medicine and Geneticsin pregnant and non-pregnant patients, and/or between the admission infections and recurrent episodes during follow-up. Methods: Blood samples were collected from 18 pregnant and 18 non-pregnant patients, who had at least two recurrent episodes during... markers. Analyses of the genetic diversity, multiplicity of infection (MOI), and a comparison of the genotypes in the samples from each patient were conducted. Results: The P. vivax parasites present in the samples exhibited high genetic diversity (6Publication Open Access Dihydroartemisinin-piperaquine versus chloroquine to treat vivax malaria in Afghanistan: an open randomized,non-inferiority, trial(2010-04) Awab, Ghulam Rahim; Sasithon Pukrittayakamee; ศศิธร ผู้กฤตยาคามี; Mallika Imwong; มัลลิกา อิ่มวงศ์; Dondorp, Arjen M.; Woodrow, Charles J.; Lee, Sue Jean; Day, Nicholas P.J.; Pratap Singhasivanon; ประตาป สิงหศิวานนท์; White, Nicholas J.; Kaker, Faizullah; White, Nicholas J.; Mahidol University. Faculty of Tropical Mediicne. Therapeutic responses across Afghanistan have not been evaluated in detail. METHODS: Between July 2007 and February 2009, an open-label, randomized controlled trial of chloroquine and dihydroartemisinin-piperaquine in patients aged three months and overPublication Open Access Efficacy of artemether-lumefantrine, the nationally-recommended artemisinin combination for the treatment of uncomplicated falciparum malaria, in southern Laos.(2012-06-8) Mayfong Mayxay; Maniphone Khanthavong; Odai Chanthongthip; Mallika Imwong; มัลลิกา อิ่มวงศ์; Tiengkham Pongvongsa; Bouasy Hongvanthong; Samalane Phompida; Viengxay Vanisaveth; White, Nicholas J.; Newton, Paul N; Mayfong Mayxay; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and Geneticsmalaria. RESULTS: Of 630 patients with P. falciparum enrolled in the trial of thiamin treatment, 549 (87%, 357 children ≤15 years and 192 adults) were included in this study. The per protocol 42-day cure rates were 97% (524/541) [96% (337/352... of patients who remained parasitaemic at day 1 after treatment was significantly higher in children [33% (116/356)] compared to adults [15% (28/192)] (p < 0.001) and only one adult patient had detectable parasitaemia on day 2. There were no serious adversePublication Open Access Thiamin supplementation does not reduce the frequency of adverse events after anti-malarial therapy among patients with falciparum malaria in southern Laos(2014-07-15) Mayxay, Mayfong; Khanthavong, Maniphone; Cox, Lorna; Sichanthongthip, Odai; Mallika Imwong; มัลลิกา อิ่มวงศ์; Pongvongsa, Tiengkham; Hongvanthong, Bouasy; Phompida, Samlane; Vanisaveth, Viengxay; White, Nicholas J; Newton, Paul N; Mayxay, Mayfong; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and Genetics.Background: In a recent study one third of Lao patients presenting with uncomplicated Plasmodium falciparum malaria had biochemical evidence of thiamin deficiency, which was associated with a higher incidence of adverse events. Thiamin... supplementation might, therefore, reduce adverse events in this population. Methods: An exploratory, double-blind, parallel group, placebo-controlled, superiority trial of thiamin supplementation in patients of all ages with uncomplicated and severe falciparumPublication Open Access Sequence variation does not confound the measurement of plasma PfHRP2 concentration in African children presenting with severe malaria(2012-08-16) Thiranut Ramutton; Hendriksen, Ilse CE; Mwanga-Amumpaire, Juliet; Mtove, George; Olaosebikan, Rasaq; Tshefu, Antoinette K.; Onyamboko, Marie A.; Karema, Corine; Maitland, Kathryn; Gomes, Ermelinda; Gesase, Samwel; Reyburn, Hugh; Kamolrat Silamut; Kesinee Chotivanich; เกศินี โชติวานิช; Kamoltip Promnares; Fanello, Caterina I.; Seidlein, Lorenz von; Day, Nicholas P.J.; White, Nicholas J.; Dondorp, Arjen M.; Mallika Imwong; มัลลิกา อิ่มวงศ์; Woodrow, Charles J.; Woodrow, Charles J.; Mahidol University. Faculty of Tropical Medicine. Department of Clinical Tropical Medicine.; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and Genetics.; Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unit.reported in both laboratory and field isolates. These issues potentially confound the interpretation of PFHRP2 measurements. METHODS: Studies designed to detect deletion of Pfhrp2 and its paralog Pfhrp3 were undertaken with samples from patients in sevenPublication Open Access Prevalence of antifolate resistance mutations in Plasmodium falciparum isolates in Afghanistan(2013-03-15) Awab, Ghulam R; Sasithon Pukrittayakamee; ศศิธร ผู้กฤตยาคามี; Natsuda Jamornthanyawat; นาถสุดา จามรธัญญวาท; Yamin, Fazel; Dondorp, Arjen M.; Day, Nicholas P.J.; White, Nicholas J.; Woodrow, Charles J.; Mallika Imwong; มัลลิกา อิ่มวงศ์; Mallika Imwong; Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unit (MORU); Mahidol University. Faculty of Tropical Medicine. Department of Clinical Tropical Medicine; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and Genetics; Mahidol University. Center for Emerging and Neglected Infectious Diseasesthe current state of drug susceptibility to the SP component, and can also provide information on the likely efficacy of other potential forms of artemisinin-combination therapy. METHODS: During the years 2007 to 2010, 120 blood spots from patients with P... to be assessed in significant numbers of patients, but these results are clearly concerning since they suggest a higher degree of SP resistance than previously detected. Further focused molecular and clinical studies in this region are urgently required.Publication Open Access A review of mixed malaria species infections in anopheline mosquitoes(2011-08-31) Mallika Imwong; มัลลิกา อิ่มวงศ์; Supatchara Nakeesathit; Day, Nicholas P.J.; White, Nicholas J.; White, Nicholas J.; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and Genetics.; Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unit (MORU)BACKGROUND: In patients with malaria mixed species infections are common and under reported. In PCR studies conducted in Asia mixed infection rates often exceed 20%. In South-East Asia, approximately one third of patients treated for falciparum... detection and speciation were tabulated. The entomological results in South East Asia were compared with mixed infection rates documented in patients in clinical studies. RESULTS: In total 63 studies were identified. Individual anopheline mosquitoes werePublication Open Access Long-term storage limits PCR-based analyses of malaria parasites in archival dried blood spots(2012-10) Hwang, Joyce; Juthamas Jaroensuk; Leimanis, Mara L.; Russell, Bruce; McGready, Rose; Day, Nicholas; Snounou, George; Nosten, Francois; Mallika Imwong; มัลลิกา อิ่มวงศ์; Snounou, George; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and GeneticsBACKGROUND: Blood samples collected in epidemiological and clinical investigations and then stored, often at room temperature, as blood spots dried on a filter paper have become one of the most popular source of material for further molecular analyses of malaria parasites. The dried blood spots are often archived so that they can be used for further retrospective investigations of parasite prevalence, or as new genetic markers come to the fore. However, the suitability of the template obtained from dried blood spots that have been stored for long periods for DNA amplification is not known. METHODS: DNA from 267 archived blood spots collected over a period of 12 years from persons with microscopically confirmed Plasmodium falciparum infection was purified by one of two methods, Chelex and Qiagen columns. These templates were subjected to highly sensitive nested PCR amplification targeting three parasite loci that differ in length and/or copy number. RESULTS: When a 1.6 kb fragment of the parasites' small subunit ribosomal RNA was targeted (primary amplification), the efficiency of P. falciparum detection decreased in samples archived for more than six years, reaching very low levels for those stored for more than 10 years. Positive amplification was generally obtained more often with Qiagen-extracted templates. P. falciparum could be detected in 32 of the 40 negative Qiagen-extracted templates when a microsatellite of about 180 bp was targeted. The remaining eight samples gave a positive amplification when a small region of 238 bp of the higher copy number (20 to 200) mitochondrial genome was targeted. CONCLUSIONS: The average length of DNA fragments that can be recovered from dried blood spots decreases with storage time. Recovery of the DNA is somewhat improved, especially in older samples, by the use of a commercial DNA purification column, but targets larger than 1.5 kb are unlikely to be present 10 years after the initial blood collection, when the average length of the DNA fragments present is likely to be around a few hundred bp. In conclusion, the utility of archived dried blood spots for molecular analyses decreases with storage time.Publication Open Access Evaluation of the phenotypic test and genetic analysis in the detection of glucose-6-phosphate dehydrogenase deficiency(2013-08-21) Duangdao Nantakomol; ดวงดาว นันทโกมล; Paul, Rick; Attakorn Palasuwa; อรรถกร ปาละสุวรรณ; Day, Nicholas P.J.; White, Nicholas J.; Mallika Imwong; มัลลิกา อิ่มวงศ์; Mallika Imwong; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and Genetics; Mahidol University. Faculty of Tropical Medicine. Mahidol Oxford Research UnitBACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is particularly prevalent in historically malaria-endemic countries. Although most individuals with G6PD deficiency are asymptomatic, deficiency can result in acute haemolytic anaemia after exposure to oxidative agents. A reliable test is necessary for diagnosing the deficiency to prevent an acute haemolytic crisis following, for example, anti-malarial treatment. The aim of this study was to investigate which method was the best predictor of this disorder. METHODS: The present study investigated four G6PD activity detections (fluorescence spot (FS), methaemoglobin reduction (MR), biochemical and cytochemical test). These methods accompanied with mutation analysis of blood samples were taken from 295 apparently healthy individuals with unknown G6PD deficiency status. RESULTS: Molecular characterization of 295 Thai adults revealed an overall prevalence of 14.2%. The G6PD Viangchan (871 G>A) was the most common (83.3%), followed by G6PD Mahidol (487G>A) (11.9%), and G6PD Union (1360 C>T) (4.8%). There were two cases of G6PD deficiency carrying the double mutations of Viangchan (871G > A)-Mahidol (487G > A) and Viangchan (871G > A)-Union (1360C > T). In comparison, the prevalence of G6PD deficiency was 6.1% by FS test and 7.1% by MR test. G6PD activity was 11 ± 2.5 IU/gHb in non-deficient females (mean ± SD), and 10.9 ± 0.6 IU/gHb in non-deficient males. The upper and lower limit cut-off points for partial and severe deficiency in adults were 5.7 IU/gHb (60% of the normal mean) and 0.95 IU/gHb (10% of the normal mean), respectively. All hemizygote, homozygote and double mutations were associated with severe enzyme deficiency (the residual enzyme activity <10% of the normal mean), whereas only 14.3% of the heterozygote mutations showed severe enzyme deficiency. Based on the cut-off value <5.7 IU/gHb, the quantitative G6PD assay diagnosed 83% of cases as G6PD-deficient. Using a cut-off number of negative cell >20% in the cytochemical assay to define G6PD deficiency, the prevalence of G6PD deficiency was closest to the molecular analysis (12.9% G6PD-deficient) compared to the others methods. CONCLUSION: The cytochemical method is a significant predictor of this disease, while FS and MR test are recommended for the detection of severe G6PD deficiency in developing countries.